Elmer r



Feb. l2, 1957 Filed Jan. 51, 1952 E R. KAISER ErAL 2,781,039

HEATERS oR- THE LIKE Foa BURNING soun FUEL s Sheets-sheet 1 INVENTOR ELMER R. KAISER AND JAMES R. GARvl-:Y

@lg man FeB. 12, 1957- E'. R. KAISER Erm. 2,781,039

HEATERS 0R THE LIKE FoR BURNING SOLID FUEL. Filed Jan.- :51, 1952 3 Sheets-Sheet 2 y "l z l 42 *43 543% Je l J/JF I @9u-*3 v 404/ g @d al l v Y Je '2:'. i i .5'8- l 1 l I I I 2 JZ 'mvEN-rcR 54a: t .(51 g 34a" ELMER R. KAISER AND .JAMES R. GAvEY @Wauw E. R. KAISER l-rAL 2,781,039

. HEATERS 0R THE LIKEFOR BURNING soun FUEL Filed Jan. a1, 1952 s sheets-sheet s Feb. 12, i957 f lNvENToR ELMER R.KA|SER Am JAMES R. GARVEY @t l f l l j' 'ml-1 100 au, W.

Unite tate HEATERS R THE LiKE FR BURNNG SQL@ FUEL Elmer R. Kaiser and .arnesR Garvey, Soiurnbus, Ohio,

assignors to Bituminous Coal Research, luc., a corporation of Delaware Application January 31, 1952, Serial No. 269,217

2 Claims. (Cl. 126-74) This invention relates to a heater or the like for burning solid fue] such as bituminous coals. More particularly, it pertains to heaters, stoves, boiler-sand furnaces to be used in residences and small buildings.

The invention provides new apparatus for satisfactorily burning bituminous coals while providing against uneven burning and the escape of fumes or smoke particularly when fresh fuel is fed to the apparatus. At the same time there is new provision made in this invention for incorporating overre air and an arch, usually of refractory material, which makes novel provision for the avoidance of breakage. At the same time, means are provided when the new heater or the like is closed to seal at least oneA of the doors to prevent the escape of fumes,v gases and smoke aforesaid. in a modilication, the opening of a tiring door also simultaneously operates the fumes, gases and smoke vent means. The new construction of this invention can readily also be made up as a round heater, stove, boiler or furnace to reduce the space occupied thereby and increase its attractiveness. These various features have long been desired particularly in connection with such apparatus capable of burning solid fuels such as bituminous coals, with their varying degrees of agglomerative and'eoking properties without loss of combustion, in'a manually operated device such as those used in many homes and small buildings.

Other objects and advantages will be apparent from the following description and from the drawings, which are illustrative only, in which:

Figure l is a view in front elevation of a heater in the form of a manually operated furnace for a home or small building, which furnace embodies one construction of this invention;

Figure 2 is a view in side elevation or the structure shown in Figure 1, said View being partly in section taken along line llkll of Figure l;

Figure 3 is a View in section taken along line Ill- III of Figure 2;

Figure 4 is a detailed View or" an overre air manifold used in the embodiment of Figures 1 and 2, said View of Figure 4 being taken generally along the line lV-lV of Figure 2 with the tiring door assembly removed;

Figure 5 is a view of the construction shown in Figure 4 taken generally along line V-V of Figure 4;

Figure 6 is a detailed view in front elevation of the arch construction in the embodiment shown in Figures l and 2;

Figure 7 is an enlarged detailed view in front elevation of the rnig door of the new structure shown in Figure l;

Figure 3 is a view in section taken along line 'vill-fill of Figure 7; Y

Figure 9 is an enlarged detailed view and partlyvin section` ofV a side elevation showing a fume and smoke vent sub-assembly in the embodiment illustrated in Figures l 2111.62;

- Figure 10 is a v iew in perspective of the sub-assembly shown in Figure 9 in partly open position;

Patented Fels.. l2, H557 Tie Figure 1l is a view, similar to the view shown in Figure 2, of a modied construction of this invention;

Figure l2 is a view in front elevation of a modified firing door and fume and smoke vent sub-assembly construction; i

Figure 13 is a View in section taken along line Xlll- Xlll of Figure l2;

.Figure i4 is a plan view of the tiring door and fume and smoke vent operator; and

Figure. 15 is a view taken along line XVXV of Figure 14.

Referring to the drawings, a furnace lll embodying a new construction or" this invention may comprise an ornamental base 11 on which a cylindrical metal shell 1'21is placed and to which it is secured by -bolting or other means. As desired shell 12 may be in ringsections with horiontzal joints or in cylindrical sections with generally vertical joints to be connected, again, by bolting or other suitable means. A dome head 13 may be provided having a'circular lower edge which is offset to enable head 13 to be seated irmly upon the top edge of shell 12. Head i3 isralso provided with an integral or detachable collar la to define an opening to a suitable stove pipe or stack for the exhausting of combustion and other gases. The lower end of shell l2 defines an ashpit 15 in the front side of which there is an opening 16 to which a frame 17 is' bolted, suitable sealing gaskets being used if desired. Frame 17 is provided with hinge brackets 18. An ashpity door i9 has ears 2li, the ears 2t) and brackets 18 being 'in line and drilled for the reception of a hinge pin 2l.' A handle 22 enables door 19 to be opened and closed. A damper plate 23 is pivotally connected at the top thereof to the face of door 19. In its closed position, damper 23 completely covers an opening 24 in door i?. By swinging damper plate 23 about its pivot all or any part et" opening 24 may be uncovered to regulate the admission oi primary combustion air to ashpit 15. Pri.- mary combustion air enters ashpit 15 through the open.- ing 2d in the quantity regulated by the respective overlapping of said opening by damper 23 and the draft through collar .14, among other factors. It will be evident that the opening or openings for such primary combustion air may be located and extend through shell 12 within the height of ashpit i5 at some location other than such openings being mounted on door i9.

A conventional grate 27 is fastened to shell l2 by any suitable means and defines the top of the ash pit chamber i5. The particular grate 27 shown is a conventional drop center grate having a fixed annular ring 23 which is the portion fixed to shell l2. The central opening at the bottom of ring 2S is closed by the grate plates 29 and Btl, lugs 31v holding grate plate 29 to ring 23 and lugs 32 holding' grate plate 3? to plate 29, suitable ash sifting and passage vopenings are provided in the respective parts of grate 27. A handle 33 extends into opening 16 so that the plates 29 and Si) can be rotated in their planes to shake down the lire. The rotation of plate 30 comes up against stops on the upper plate 29 so as to rotate thatplate also, there being a lost-motion action between the respective plates as will be well understood. Other conventional forms of grate may also be used.

Shell l2 above ring 28 is lined with refractory wall sections 34, there being vertical joints provided between the respective arcuate sections required to line shell i2. rlhese arcuate refractory sections will be of diff ferent heights. Thus, sections 34a will be slightly higher than sections Sb but will not be as high as the sections 3de. HVThe lower Vends of the refractory sections may be rmly supported on the annular flange of ring 28 as shovvnin Figure 2 and, if desired, the radially extendedwjoints between the refractory sections may be cemented with asbestos cement when the furnace 10 is assembled. The refractory lining sections 34e are set back adjacent their lower ends at the level 35 to provide a recess between the forward edges of those sections above level 35 and the rear vertical surfaces of sections 34a into which a refractory arch 36 may be slidably inserted and supported.V

Arch 36 may be made in two or more parts 37 and 3S, the adjoining surfaces of the respective parts 37 and 38 having a spaced or undercut portion relative to one another to provide a slot or gap 39. Slot 39 is usually far enough above grate 27 to be out of the zone of active combustion. The respective parts 37 andV 38 may directly engage one another at the ends 40. In order to provide uniform loading of the lower brick 3S, asbestos or cardboard ller may be inserted in slot 33 during the assembling of the new device thereby evening out the usually uneven surfaces of the tired vrefractory brick such as the parts 37 and 3S comprise. Such uniform loading prevents undue stressing of the yrespective parts of the arch 36 particularly in the course of the use of the new device. And, arch part 38 which is subjected to the severest conditions has relative freedomV to expand and contract relative to part 37. Similarly, there is suicient clearance in the arch supporting wall recesses in wall 34C above level 35 to avoid spalling of the refractory due toexpansion and contraction forces obtaining in the course of operation. On the other hand, if part 38 in the course of use should burn `out or Warp, in general it will only be necessary to lift Vout andreplace part 38 and not to replace the entire arch 36. Moreover, as shown in Figures and 6, rectilinear blocks may be employed for arch 36 rather than requiring fabrication of special refractory shapes.

The bottom surface of arch 36 which is at level 35 denes with the vertical walls immediately below level and with grate 27 a combustion gases outlet 41 through which the combustion gases iiow before entering an upwardly extending segmental passage 42 between the rear surface of arch 36 and the insides of the refractory wall members 34C. The wall members 34C may be provided with one or more openings or ports 43 which also extend through those portions of shell 12 in alignment therewith to serve as secondary air ports Vto complete the combustion of any incompletely burned material in the gases passing beneath the arch 36. The gases continuing upwardly through passage 42 strike a bale 44 fastened to the inside of head 13.

Baffie 44 directs such gases forwardly so as to bring them into contact with the entire interior of head 13, which is usually not insulated. Thereby, the transference of heat to the radiating surface comprising the wall of head 13 is correspondingly increased. Thereafter, the gases pass out through collar 14 and into the stack or stove pipe connected thereto leading to such a stack. A combustion chamber 45' exists in and may be defined by the front surface of arch 36 and the insides of the refractory walls 34a and 34p. The lower portion of that combustion chamber extending from grate 27 to arenoso forms therewith a generally inverted L-shape. The inner wall 51 of that L-shape slightly overlaps the top' Similarly, wing sections S3 of such a manifold are Y fastened to the upper end of shell 12 and form a partly stepped-up arcuate continuation of manifold between the ends thereof and the arch 36. The manifold sections 53 have a downwardly extending wall54 inwardlyV spaced from shell 12 and overlapping the top edges of the inner lsurfaces of the refractory wall sections 34a. lf desired, plates may be Vused to close the ends of the manifold sections 53 next to manifold 5) in that portion of those ends above the top of manifold 5t). ri'he vertical overlap between the interior of manifold 5t) and the interiors of the wing manifolds 53 causes some of the air entering slot 49 to ow into the sections S3 and out of holes 55 in walls 54. Thereby, the annular distribution downwardly into chamber 45 of overfire air is caused to occur around entire periphery above the tops of the walls 34a and 34b. Such overfire air assists in keeping the fuel in the upper part at least of chamber 45 from becoming ignited or agglomerating to an undesirable extent and also provides an available supply of oxygen.

The front of head 13 is provided with an opening 56 Y the side edges of which are in registry with an opening a position above level 35 will usually constitute the zone Y of active combustion, whereas the upper portion of the combustion chamber 45 will-constitute a storage or magazine space for unburned and possibly unignited fuels such as the bituminous coal depicted in Figure 2. A duct 46 may be provided and attached to the front Vof* shell 12. Duct 46 is open only at `the bottom and is provided with a butterfly damper Valve 47 therein controlled by a knob 4S to regulate the amount of air permitted to flow through duct'46. A slot or port 49 extends through shell l2 adjacent the upper end of duct 46 soV as to place the interior of that duct in communication with Ythe interior of furnace 10. Air entering furnace 1t)V through duct 46and slot '59 maybe termed overre air. It passes into the interior of the central section S@ of a manifold. Manifold Si) is fastened to the upper end of shell 12 by any suitable means and' 57 in the front of the upper part of shell 12. Openings 56 and 57 define a doorway which is adapted to be closed by a ring door 5S. A sealing frame S9 is bolted or otherwise secured in position around the edges of doorway 56-57 respectively to shell 12 and head 13. Frame' 59 is provided with a continuous annular outer edge 60 and continuous inner annular edge 61. Thus, flanges 60 and 61 define the inner portion of a sealing recess 62, which portion 62 opens into the interior of head 43 through an opening 63. Firing door 58 is provided with ears 64 which overlap lugs 65 integral with frame 59. An opening is provided in registry through the ears 64 and lugs 65 through the insertion therethrough of hinge pin 66, the respective angle of which may be so set as to normally cause door 53 to swing closed under the influence of gravity.- Door 58 is provided with a continuous outer edge 67 extending toward ange 60 for mating engagement therewith when door 58 is closed, the respective lianges 67 and 6@ being in contact around the entire peripheryV of doorway 56-57. Similarly, a continuous inner flange 63 integral with door 58 extends toward ange 61 for mating engagement therewith when door 58 is closed. Thereby, a recess 69 defined by the flange 67 and 68 completes, with recess 62 the entire sealing recess. As a consequence, during operation when door 58 is closed, any gases or fumes which may pass outwardly through doorway 56-57, must pass into sealing recess 62-69 and since that recess is at a pressure slightly less than atmospheric because of the open communication therewith through opening 63 with combustion gases chamber 7l?. All such gases or fumes will be drawn into chamber 70 which normally is at lower pressure and pass out through collar 14 to the stack or chimney. The seal between door 58 and frame 59 around the mating edges of franges 61 and 63 is suiciently tight to prevent any undue disturbance of the flow of overtire air through the manifolds Si) and 53 downwardly into combustion chamber 45. A handle 71 is normally used to open and close door 58. If desired,

door 58 may also be provided with a latch ear to coact with a latch strike on frame 59.

Chamber 70 is sealed oi from combustion chamber 45 and doorway 56-57 by a partition 72 extending from the top of arch block 37 to the interior of head 13 to the top of the aforesaid doorway thereby forming a dierential pressure chamber with respect to the combustion chamber 45. Partition 72 is bolted or otherwise suitably fastened to head i3 and the joints between partition 72 and any other parts such as frame 59 and block 37 may be suitably sealed as by means of a furnace cement. Partition 72 is provided with a vent 73 forming a passage at selected times for the exhausting of gases, fumes and/or smoke from the top of combustion chamber 45 into chamber '76. Around vent opening 73 partition 72 is provided with a continuous upstanding integral flange 7e forming a seat for a vent closure 75, as morey clearly shown in Figure 9. Forwardly extending ears 76 coact with lugs 77 fastened to partition 72 by means of a pivot pin 7S passing through aligned openings in the adjacent pairs of ears 76 and lugs 77. An arm 79 is welded or otherwise fastened to closure 75 for engagement by a bent link 80 which extends through an opening 81 in arm 79 above the axis of the pivot pin 7S. As will be evident from Figure 9, the rearwardly extending portion of link dit passes through an opening in the flange or" frame 59 and a registering opening in head i3 into chamber 76 to a position where it can pass through opening 8l as aforesaid. A nut S2 may be screwed on the inner end of link i to prevent any accidental disassembling of the parts. he outer end of iink S is bent into the form of a hook 83 which passes around a headed stud 84 fastened upright in the upper ear 64 of door 5%. Hence, as the opening of door 58 is begun, stud 84 pulls on link Sil to begin the opening of closure 75 thereby directly exhausting to chamber 70 the space inside furnace 19 adjacent doorway Sti- 57, causing all gases r'iowing in that vicinity to pass through chamber 76 in vent 73. Twhen door is closed, the Weight of closure '75 seats it relatively tightly on ange 76 closing vent 73. Sufficient clearance spaces between the various elements or" the linkage are provided to take care of the respective movements of the parts involved without deliection of them as, for example, where link S passes through furnace shell 12 and frame 59. The

provision of a head on stud S4 avoids any likelihood of y hook S3 becoming disconnected from part 84.

Head 13 and shell l2 as shown in Figure l are respectively provided with guide brackets 85 through which a rod 86 slidably extends. rl`he upper end or rod 86 is in the form of a spatula S7 closely adjacent to and beneath that portion or link Si? which is outside of furnace 1G as shown in Figures 9 and l0. In its lower position, end S7 is just out of contact with link S0, or, in any event does not lirt link S0 so as to unseat closure 75. forming an end S3 which passes through an eye 89 of a crank 9i?. CrankV 9% is held in bearings 91 bolted to base 11. The other end of crank 99 is provided with a foot pedal 92. Hence, by stepping on pedal 92 eye 89 is raised raising rod S6 and end S7 and thus pushing link Sil upwardly, the hook 83 pivoting under the head of stud S4 to open closure 7S as shown in Figure l0. A split set collar 93a is provided on rod S6 at an approximate height so that when the pressure is removed from pedal 92 the weight of the rod 36 will cause it to fall out of engagement with link Si?, rod S6 coming to rest when collar 93a butts against upper bracket 85. Normally, pressure will be removed from pedal 92 only after door Sbas been opened, which opening will take over the maintenance of vent 73 in open condition by holding closure 7S up away from flange 74 through arm '7-9, link 39 and stud 34. When door 5S is then closed, closure 75 will close and seat itself on flange 7d since the operators foot has theretofore usually been removed from pedal 92.. 'the advantage or pedal 92 and rod S6 sub-assembly is that vent 73 can be opened, if desired, in advance of tiring door S8 thereby further insuring against any discharge of gases, fumes, vapors or smoke from combustion chamber into the room or space in which furnace l@ is located.

The lower end of rod S is bent at right angles A modiication ofthe new construction of this inveii.

tion is illustrated in Figure ll. The parts thereof gener-I ally corresponding in construction and functioning are correspondingly numbered with the addition of a prime accent thereto. ln supplying combustion air, a duet t64V is utilizedY in cooperation with a port 94 intermediate ring 2S and port 49. An adjustable buttery valve 93 is interposed in the lower part of duct 46 and may be used to adjust all air enteringl duct 46 including such combustion air. The primary combustion air entering port 94 passes downwardly through a slot 95, which is arcuate in pian, in wall section 34H. An arcuate slot 96 inring 28 permits such primary combustion air to pass into ashpit 15' and upwardly thorugh grate 27 into the active combustion zone of the iire adjacent that grate. Thereby, the primary combustion air is preheated' by convection against the surfaces of slot 95. Normally, the modification shown inV Figure l1 would be used with furnaces or boilers of larger capacity in terms of heat output` where such larger capacity is required.

The remainder of the air passing through port 94 in shell 12 acts somewhat in the nature of crossre air and proceeds through anY inwardly directed' opening 97 passing entirely through wall 34h. Such crossiire air enters combustion. chamber i5 adjacent theV top ofthe active combustion zone and may assist in attaining relatively higher rates of burning than those attainable by' the use of theV embodiment illustrated in FigureA 2.

A modied iiringV door and smoke and furne subassem'- bly made in acordance with the teaching of this invention is illustrated in Figures l2 to l5, inclusive and may be used in connection with the structures shown in Fig# ures 2 and ll in lieu of the particular construction illus:- trated therewith. ln the modiiied sub-assembly, a-iringdoor 109 is provided and conventionally' hingedrto a frame 161 corresponding in general construction and functioning to door S8 and frame 59, respectively. Thus, anV annular sealing recess or channel 192 is in connection with a heating and ilue chamber 70 through an opening 103 respectively through frame 191, and head 13". A partition 72" is also provided similar in general construction and functioning to partition 72. In the doorway defined by the opening through frame lill a smoke cu-rtain M54 in the form ot a hanging plate may be provided. Pivots 19S pass through lugs 106 and adjacent ears 107 respectively on frame itily and plate M4. The t between swingable hanging plate ii and opening lla' is suciently close to act as a balile or barrier for the upper part of opening lola. Hence, if there should be any tendency when door 199 is opened for fumes, gases or smoke to issue through opening lola, they will be im? peded by plate'ltldV and generally directed inwardly again facilitating their removal throughk a vent 73" in partition 72".

rthe lower part or frame itil is providedwith lugs 108 adjacent ears 169. Ears 3&9 are integral with a chute llo, pivot pins 1li joining chute llt) swingably to'frame lol. The width or` chute lit) is also sutcient to till up when in the position shown inFigure 13 substantially le entire remainder ot opening lilla when taken in conjunction with curtain Eile. Thus, in the position shown in Figure l3 curtain iti-i and chute 110 shield the inner surface of door to@ and thereby materially minimize the deposit thereon of soot or other layer of impalpable solids which might catch i'lre outside of furnace l!) when door le@ is opened. When door 160 is opened, chute 1l@ under the inlluence of gravity falls into the position illustrated by the reference numeral 11th/z as shown in dot and dash lines in Figure 13'. Thereby, it facilitates the charging of combustion chamber 45 with solid fuel and shields the lower edge of opening lilla whereby door 168 may be readily closed after the fuel-charging operation. When door is opened, curtain 104 remains generally in the position arenoso shown in Figure 13 but if for any reason the full opening 101eV is required curtain 104 can be raised by swinging the lowerend Vthereof outwardly through opening 101m On each side of frame V101 there is a Vstop 101b integral therewith which prevents kcurtain 104 from swinging inwardly of the position shown in Figure 13. The upper end 110b of chute 110 is so constructed that inthe position shown in full lines of Figure 13 with door 100 closed, such end rests against the lower end of curtain Y104 to complete the shielding aforesaid of the inside of door 100. The raising of chute 110 into the'position shown in full lines in Figure 13 is performed by the act of closing door 100. As door 100 is swung into closed position a cam 112 engages the exterior of the curved end 110!) swinging chute 110 upwardly Y from the position 110:1 into its position 110 shown in Y solid lines in Figure 13. vIntegral brackets 110e` on the outer side chute 110 limit the outwardly and downwardly movement of chute 110 to cause it to rest in the position shown in dot and dash lines 110a in Figure 13.

Door 100 is provided with an integral latch wedge 113 for engagement `by a registering wedge surface 114 the latter of which is integral with a handle 115 pivoted at 116 to shell 13". Handle V11S is provided with an integral extension 117 to operateY a crank 118 through a linkV 119 pivoted respectively to arm 117 and crank 118.

Shaft 120 of crank 118 extends through shell 13" and is supported in a tubular bearing 121. The inner end 122 of crank 118 is pivoted and provided with an eye through which the upper link of a chain 123 is fastened. The lower end of chain 123 passes through the upstanding eXtensionof arm 79". Arm 79" is fastened or otherwise secured to closure 75". Hence, the act of unlatching door 100 by raising handle 115 in the direction of arrow shown in Figure 12 also and simultaneously raises closure 75" into the position shown in dot and dash lines in Figure 15 to vent any gases, fumes and/or smoke which might tend to drift through opening 101:1 as door 100 is being opened or while it is open.

- Although the foregoing embodiments of this invention are illustrated in connection with a -gas-to-gas type of heat v transfer, it is evident that the walls `off the embodiment shown may in part or substantially entirely be composed of water cooled sections, for example, for the generation of steam 'or ythe heating of water for a hot water heating system. Moreover, particularly the upper part of the new karch construction of this invention may be a water cooled or boiler section for gas-to-liquid heat transfer. In addition, the combustion gases may be led to other types of heating transfer surfaces, a particular advantage of the embodiment shown being that they can be constructed in the form'of very compact round or rectilinear heaters of attractive lappearance for residential and other relativelly low-duty uses.

This invention may be variously practiced without departing from the spirit thereof as dened in the appended claims.

We claim:

1. In a heater or the tlike for burning sol-id fuel, in combination, a round shell, a combustion chamber inside said shell, a combustion gases passage inside said shell, said pass-age being defined by a refractory arch associated with said shell,ra gas outlet beneath the bottom of said arch connecting said chamber and said passage, a duct on Ythe outside of said shell, a port through said shell communicating with the interior of said duct and supplying overre fair, la manifold extending around the top of said combustion chamber, the interior of said manifold being in communication with said port, 'annulanly spaced openings between the interior of said manifold Vand said combustion chamber, a grate adjacent the bottom of said combus-tion chamber, a firing door 4adjacent said manifold, spaced anges on said tiring door extending toward said heater to provide a sealing recess, a combustion gases dome above said passage to define a combustion gases chamber in communication with said sealing recess, a partition between said last-mentioned chamber and said combustion chamber, a fume vent assembly in said partition linkage means for placing said combustion chamber in communication with said combustion gases chamber before said firing door is opened, and linkage means between said tiring door and said assembly to atleast hold said fume vent assembly in open position while said tiring door is open.

2. in a heater or the like for burning solid fuel, in combination, a round shell, a combustion chamber inside said shell, a combustion gases passage inside said shell, said passage being defined by a removable p-artible planar refractory arch associated with said shell, a gas outlet beneath the bottom of said arch connecting said chamber and said passage, a duct on theoutside of said shell, a port through said shell communicating with the interior of said duct to supply overre air, a manifold extending around the top olf said combustion chamber, the interior of said manifold being in communication with said port, annularly spaced `openings between the interior of said manifold and said combustion chamber, a grate adjacent the bottom of said Ycombustion chamber, means for supplying primary combustion air through said grate, means for supplying secondary air adjacent the bottom of said arch, a normally closed tiring door adjacent said manifold, spaced flanges on said ring door extending toward said heater to provide a sealing recess, a combustion `gases domeabove said passage to define a combustion gases chamber in communication withY said sealing recess, a partition between said last-mentioned chamber and said combustion chamber, and means for placing said combustion chamber in communication with said combustion gases chamber when said ring door is open.

References Cited in the tile of this patent UNITED STATES PATENTS 169,601 Treadwell Nov. 2, 1875 378,979 Schlapp Mar. 6, 1888 600,795 McLean Mar. 15, 1898 Y 789,611 Jackson May 9, 1905 Y 843,106 Roel Feb. 5, 1907 902,714 Cope Nov. 3, 1908 914,923 Cahoone Mar. 9, 1909 953,465 Howard Mar. 29, 1910 1,339,571 Mersfelder May 11, 1920 1,469,600 MacKenzie Oct. 2, 1923 1,561,497 Wier Nov. 17, 1925 1,739,907 Kohout Deo. 17, 1929 2,352,057 Wingert June 20,1944 Y 2,400,901 Agricola et al May 28, 1946 2,419,379 Tindell Apr. 22, 1947 2,545,680 Wyatt Mar. 20, 1951 2,564,713 Miles Aug. 21, 1951 FOREIGN PATENTS 164,761 Germany Nov. 2, 1905 79,657 Australia Dec. 29, 1919 255,679 Great Britain July 29, 1926 540,275 Germany Dec. 19, 1931 Y 647,017 Germany June 25, 1937 630,224 Great Britain Oct. 7, 1949 

